Window shade construction



c. e. BARRC JWS WINDOW SHADE CONSTRUCTION Nov. 14, 1950 5 Sheets-Sheet 1 Filed April 22, 1946 lElm m 8 m mm W M We A j. 4 r m 6 .2 M KJL m Q m Nov, 14, 1950 c. G. BARROWS WINDOW SHADE CONSTRUCTION Filed April 22, 1946 C- G. BARROWS WINDOW SHADE CONSTRUCTION Nov. 14, 1950 3 Sheets-Sheet 5 Filed April 22, 1946 INVENTOR Clarence GI ,Barrows Patented Nov. 14, 1950 WINDOW SHADE CONSTRUCTION Clarence G. Barrows, Hamden, -Conn., assignor to The Safety Car Heating and Lighting Company, Inc., a corporation of Delaware Application April 22, 1946, Serial No. 663,794

16 Claims.

This invention relates to window construetions. More particularly it has to do with constructions of the double glazed hermetically sealed type wherein a shade is positioned within the enclosure between the two panes of glass and wherein means are provided for operating the shade by a handle which extends to a point of access outside the sealed enclosure. The present invention relates to the invention disclosed and claimed in my copending application Serial No. 544,721, filed July 13, 1944, Patent No. 2,461,870 issued February 15, 1949.

Various novel window constructions have been introduced into use in railway cars. Some of them have found their way into office and factory buildings,especially where air conditioning is available; some have been used in home constructions. It is now common to find a window of the double glazed type. Such windows have the advantage not only of insulating the interior from atmospheric temperature extremes existing outside but also they reduce the passage of sound through the closed window. They have as one disadvantage a tendency to become cloudy through the condensation of moisture on interior surface portions of the glass in regions where it is not possible to wipe or clean the glass.

In my application above-mentioned I proposed a window construction of the double laze'dltype wherein window shades are positioned within the hermetically sealed enclosure formed between the window panes. With my present invention I provide an improved window construction wherein a novel arrangementof shades is provided within the sealed enclosure. With this construction I have incorporated a shade operating mechanism such that the window shades can be readily positioned and adjusted while at the same time the interior of the window enclosure where the shades are located is maintained in an airtight condition. My construction also includes a valve which may be opened to exhaust the air within the sealed enclosure and to refill the enclosure with clean dry air. Thus, the panes may at all times be maintained clean and in a transparent condition.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts and methods of operations as will be exemplified in the structures and sequences and series of steps to be hereinafter indicated and the scope of the application of which will be set forth in the claims.

In this specification and the accompanying drawings, I have shown and described a pre ferred embodiment of my invention; but it is to be understood that this is not intended to be exhaustive nor limiting of the invention, but on the contrary is given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify and adapt it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings:

Figure 1 is an elevation on a relatively reduced scale of a window construction embodying the invention;

Figure 2 is a "broken vertical section taken through the construction of Figure 1 along the line 2-2;

' tion;

Figure 8 is a view similar to that of Figure 1 showing a window unobstructed by any shade portion;

Figure 9 is a view similar to that of Figure 8 showing the window with the shade partially lowered from the top thereof and,

Figure 10 is a view similar to that of Figure 8 showing the window with the shade partially raised from the bottom thereof. I

Referring to Figure 1, a window unitgenerally indicated at 20 is formed by two panes of glass 22 and 24 (see Figure 2) rigidly mounted in a metal frame 26 the panes and the frame are sealed to form an airtight compartment or sealed enclosure. As shown best in Figure 4, frame 26 has four corner brackets 21, 23, 25 and 2'! connected by top, bottom and side channel members 29. Between the panes of glass and forming a border adjacent the frame (Figure 1) are sheet metal border pieces 28 and 30. These border pieces form a channel within which is positioned the operating mechanism for the shade assembly. The shade assembly is formed by an upper roller 32 upon which is rolled an upper shade 36 (Figure 2') and a lower roller 34 upon'which is rolled a lower shade 38, and at the 2), the tapes are wound onto the lower roller 34 and the upper shade is unwound andpulled down so as to cover the window progressively from the top downwardly. In a like manner, counter-clockwise rotation" of the rollers winds the tapes onto roller 32 and unwinds the lower shade 38 and pulls it up so as'to cover the window starting from the bottom and progressing upwardly.

Centrally positioned at the bottom of the window is a' knob '44 whichis rotated to raise and lower the shades as desired. As shown best in Figure 3, knob 44 is fixed to awcontrol=shaft 46 which is carried .by a self-aligning pillowsblock 48 mounted on the window sill:i59.5 The .end of shaft 46 projects into a. gear box 52 which is fixed to the lower surface'of window frame 26. Gear box 52 is sealed: around its upper rim to the lower surface of frame and registering openings in the adjacent 'walls connect the interior of the gear box to the sealed-enclosure within the frame. a 1

Referring to Figures 4 and 5, the extreme end of shaft 46 is cut away on opposite sides to pro vide a spline head 56 which is snugly received in a recess in a cylindrical clutch plate 58. Clutch plate 58 is held in a cylindrical pocket 53; in casing 52' (Figure andis urged to'lthe right by a Spring 6 which-in; turnis held'in place by a spring retainer 66. The right-hand end face of clutch member 58 is provided with an annular row of clutch teeth 5l and these teeth'mate with similar teeth 59 on the adjacent end of a driving spindle 69. Spring 64 urges clutch plate 58 to the right so that teeth 51 normally interengage teth 59 and a clutch drive is-thereby formed. However, excessive torque on this clutch drive causes'teeth 51 toride-up thesides of teeth 59 with the result that the clutch is: disengaged; then spindle 60 remains stationary even though shaft 46 is turned; a

Spindle 6B is positioned in a tapered ghole through the bottom wall of pocket 53 and'the spindle has a tapered portion which provides a frusto-conical sealing surface which mates with the similarly shaped surface l2 of-t'he tapered hole. Proper lubrication on these surfaces insures an air-tight seal at these surfaces so that a shaft-seal, barrier is "formed. At its right-hand end spindle 60 carries -a gear 54 which is keyed .to the spindle by a key 68 to provide a positive drive connection, but the key slot in spindle 5D. is slightly larger than the key so that the spindle may slide axially within the gear. The extreme end of spindle 65! "is supported in a bearingrecess 63in the wall ofgear box 52. 1 Thus, spindle fifl-and gear 54" are rotatably mounted by the-tapered-. surface"IZ and bearing recess 63 and a positive driving connection is providedfor the'gear.

As pointed out above, gear-box 52 forms part of the sealed-enclosure of the window, and a fixed seal is maintained except "at thershaft seal formed by mating'surfaces "l0 and-l2 around spindle 60. "However, these mating Surfaces are also the valve surfaces which are separated to provide for the exhausting of the enclosed space and the refilling of this space with clean dry air. Thus, spindle 68 acts as a sliding valve and the surrounding wall provides the valve seat. Spring 54 holds the valve closed by urging clutch plate 58 and spindle to the position shown and the valve may be opened by sliding the spindle to the left. t

It is thus seen that a shaft seal is provided which is also a valve and at the same time the structure forms a self-releasing clutch assembly between the driving shaft 46 and gear 54. In this waythe normal turning movement of shaft 46 is transmitted by the spindle through the wall of the gear box into the sealed enclosure so that gear 54 is rotated. But when there is excessive torque caused by resistance to turning movement of gear 54, the clutch is released and shaft 46 turns while gear 54 remains stationary; the releasing of the clutch does not break the shaft seal.

Within the sealed enclosure a gear train is provided which transmits the turning movement of gear 54 to the rollers 32 and 34. Accordingly, as shown best in Figures 4 and 6, within gear box 52 and parallel to spindle 68 is a shaft 14 which is mounted at its ends in the gear box walls and upon which is mounted to rotate freely a pinion gear it. Pinion gear 16 meshes with gear 54 and (Figure 6) has a hub extension '18 at the left upon which is-rigidly fixed a bevel gear 80. Bevel gear 88 meshes with a bevel gear 82 which is mounted upon and fixed to the lower end of a stud shaft 84. Stud shaft 34 is Journaled in a sleeve bearing 85 in the top wall of the gear box. Fixed to the upper end of shaft 84 is a bevel gear 86 which (see Figure 4) projects above the bottom wall of frame-26.- In this way a positive-drive gear train is provided between gear 53 and bevel gear 86 so that the movement of spindle 68 is transmitted to this bevel gear.

Bevel gear 86 meshes with a similar bevelgear HUwhich is keyed to the end of a shaft 92. Shaft 92 is supported at the left in a, sleeve bearing 93 and near its center in a similar sleeve bearing 94, and at the right the shaft carries a; coupling sleeve 96 which is fixed to the shaft by a pin9l and the-right end of which receives the end of a stud shaft I09. Stud shaft is journaled-in a pair of hearings in corner bracket 21 and this provides additional support for shaft 92. Shafts 92 and I99 are coupled-by a spline 98 so that shaft I00 turns with shaft 92. Keyed to shaft Hill is a gear I82 which meshes with an intermediate gear Hl4 also journaled in corner bracket 21 and in turn geared to a gear "16. Gear N16 is keyed to a stud shaft 105, journaled in corner bracket 21, which projects to the left where it is connected through a spline Hi to a roller shaft I08. 1

The interengaging ends of shafts I05 and I08 are snugly received in the hub of a bevel gear I [6 which is connected to shaft 108 by apin I09. Roller 34 is mounted on shaft I08 by a pair of end plates H2 which are fixed to the roller and are free to rotate on the shaft. End plates H2 carry flange plates Hi), the peripheries of which extend above the surface of the roller to guide the shade as it is received by the roller. At its left-hand end the-roller assembly is removably supported by a sleeve H3 fixed to the end of shaft I08 by a pin and a stud bolt I I5 which is screwed into a threaded hole in corner bracket 2| of frame 26. The reduced end of the stud bolt is snugly received in the sleeve so as to provide a bearing support and the end of the roller may be released by removing the stud bolt. Coiled within the right-hand end of roller 34 is a coil spring 4 which is attached at oneend to shaft I 08 and at the other end to the adjacent end plate II 2 and thus to the roller. Spring I I4 provides a resilient drive between shaft I08 and roller 34; Thus, the roller tends to turn with. the shaft and the resilient drive provides advantages which will be more fully apparent below.

Bevel gear vI l6 transmits the rotation of shaft I03 to roller 32 and for this purpose bevel gear II6 meshes with a bevel gear I1 3 keyed to a shaft I20. Shaft I is journaled at :its lower end in a bearing I22 carried by frame 2.6 and at its upper end by a pair of bearings I23 and 1:25 in corner bracket 25. At its upper end shaft I20 carries a bevel gear I24 which is fixed to the shaft .by a pin I2! and bevel gear I24 :meshes with a bevel gear I26 similarly attached by a. pin I29 to @a roller shaft 128,. Roller shaft I28 is journaled at its right-hand end in a bearing l3I left-hand end of roller shaft I08 by a sleeve- I35. and :a stud bolt 13.1 which are similar in structure to sleeve I I3 and stud bolt I I5. Roller 32 is supported at its ends by a pair of end plates I33 which are fixed to the roller and'whi-ch carry flange plates, I31 which are similar to flange plates ,I II). A coil spring 130 in the left-hand end of roller 32 has one end attachedsto the roller and its other end attached to the adjacent end plate. This spring. provides a resilient .drive between shaft 128 and rol1er r3;2 which is. similar to the drive provided for roller 34 by spring I I4.

1 In the drawings the .elements are shown positioned so that each of the shades is fully wound onto its .roller and by turning knob 44 clockwise, the lower roller 34 is caused to wind tapes 410 and 42 onto itself whereas the upper r.oller..32 is :unwound and the upper shade 36 is drawn down to cover the window from the top. Counter-clockwise rotation of knob 44 reverses the direction. of rotation of the rollers so that tapes 14.0 and 42- are wound onto roller 32 and the lower shade. 38 is drawn up to cover the window from the bot tom. The winding ofpthe shades onto the rollers increases their effective diameters so that when the shade is being unwound from one of the rollers and the tape is being wound onto the .oth-- er roller there is a tendency for the tapes to wind more rapidly than the shade unwinds; that is, with the roller shafts geared directly together the larger diameter winding surface tends to take up the tapes at an increasing rate, whereas the smaller diameter unwinding surface on the other :rolier tends to unwind the shadeat a decreasing rate. However, the resilient drives formed by springs I14 and 130 between the rollerslight stretching, expansion and contraction as might occur during use.

It is desirable to provide limits for the winding operation so that when either the upper or thelower shade completely covers-the window, the

only possible operation is the rewinding of. this Thus, as shown best.

shade onto its own roller.

in Figure 4, shaft 92 :is provided at its; central portion with a thread I32 and carriedzby thread.

I32 is a nut I34. Nut I34 has a pair .ofinteg-ral radially projecting lugs (see Figure 2) which slide along the upper surface of the channel member 29 and these lugs prevent nut I32 from rotating. Thus, when shaft 92 is rotated nut I34 travels along the shaft, and due to the direct gearing between shaft 92 and theroller shafts,

the position of nut I 34 is an indication of the window, nut I34 engages the stationary bearing.

94 which acts as a stop. Continued clockwise rotation of shaft 92 is resisted sufficiently to cause the releasable clutch (Figure 5) formed by teeth 51 and 59 to be disengaged with the result that the turning of knob 44 does not turn shaft 92. Extended rotation of shaft 92 in the reverse direction moves nut I34 against sleeve 96 which acts as a stop and limits rotation in the opposite direction.

In Figure 7 a fittin is shown by means of which the air may be withdrawn from the sealed enclosure and replaced with clean dry air. With this arrangement shaft 46 is removed by releasing pillow block 48 (Figure 3) and withdrawing the shaft from'its normal position in pocket 53, and then inserting a fitting I36 into the pocket. This fitting has a threaded shank I38 which is turned into a threaded bore MI in spindle 60. The initial threading of shank I38 into bore I 4| draws the shoulder of an enlarged portion I39 and a sealing washer I40 against the periphery of the mouth of pocket 53 so that an airtight seal is provided around the pocket. Thereafter, continued threading of the shank into the bore I 4| pulls spindle 60 to the left against the pressure of spring 64 and thereby unseats the valve and provides an annular air passageway between surfaces'lfl and 12. g f

Fitting I36 has a tee connection at its outer end with air suction being connected at one side through a suction tube I42 and with a source of clean dry air under pressure being connected through an air-pressure tube I44. A three-way valve I46 is manually controlled to regulate the alternate connection of tubes I42 and I44 to a central bore I41 which is open at its right-hand end to the interior of pocket 53. Thus, with valve E46 in the position shown, air from the enclosed space is drawn through the passageway formed between surfaces 10 and I2 into pocket 53 and thence through bore l4! to the suction tube I42. With valve I46 turned clockwise approximately ninety degrees from the position shown, passageway I 41 is connected to the airpressure line I44 and air reenters the enclosure through passageway I41, pocket 53 and the passageway between surfaces 10 and I2. Thus, it is a simple matter to evacuate the enclosed space and to refill it with clean dry air. In order to insure that the enclosed space will be kept dry,

the hollow shell of each of channel members 29 is filled with a desiccant I48. Thus, any mois-v ture which enters the enclosed space is immediately adsorbed'so that the windows are kept clean and moisture-free.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore setforth or shown in the accompanying 7 drawings is to be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a window construction, the combination of, a pair of window panes positioned in spaced parallel relationship, a rigid frame construction providing mounting means for said panes and forming with said panes a sealed enclosure, a pair of shade rollers rotatably mounted within said sealed enclosure in parallel relationship respectively at the top and bottom edges of said panes, a pair of shades wound respectively on said shade rollers, a pair of connecting strips at the respective side edges of said panes connecting the free ends of the two shades together whereby the complete winding of the strips onto one roller unwinds the shade from the other roller and draws the shade between the panes to cover the window, a gear assembly to rotate said rollers and thereby wind and unwind the shades as desired, and means to operate said gear assembly.

2. A window construction as described in claim 1 wherein said gear assembly includes a horizontal shaft within the enclosed space adjacent the lower edge of said panes and having a threaded portion, a nut threaded onto said threaded portion and adapted to move axially with respect to said shaft, means to prevent said nut from rotating, and means constituting a pair of stops -positioned along said shaft and providing limits for the movement of said nut therealong.

' 3. A window construction as described in claim 1 wherein each of said rollers is mounted to rotate upon a driving shaft, and a coil spring within the roller coiled about said shaft and attached at one end to said shaft and at the other end to said roller whereby the roller is driven by a resilient drive from the shaft by the spring.

4. A window construction as described in claim 1 which includes a shaft-seal assembly mounted in the wall of the frame construction and providing driving means connecting said gear assembly to be operated from outside the sealed enclosure, said shaft-seal assembly including, means fixed to the wall and defining an opening presenting a stationary frusto-conical surface, a spindle rotatably mounted in said opening and having a mating surface which forms with said frustoconical surface a shaft-seal barrier, and means urging said spindle in an axial direction whereby the mating surfaces are held together.

5. A Window construction as described in claim 1 wherein said gear assembly includes, a gear within said sealed enclosure, a spindle rotatably mounted and providing a mounting for said gear with the spindle and the gear keyed together and the spindle slidable axially within the gear, said spindle projecting through a tapered opening in a wall of said frame construction, the spindle and the opening having mating frusto-conical sealing surfaces which provide a shaft seal, said spindle carrying on its end surface outside of the sealed enclosure an annular row of clutch teeth, clutch plate. mounted adjacent the last named end of said spindle and having an annular row of clutch teeth which interengage the clutch teeth on the spindle to provide a driving connection, and a coil spring urging said clutch plate against the end of said spindle whereby said teeth are held interengaged and also urging said spindle toward said opening whereby the mating surfaces are held together.

6. A window construction as described in claim 1 wherein said gear assembly includes, a releasable clutch formed by a clutch plate and a spindle which are held together by a coil spring, said spindle being mounted in an opening in the wall of said frame construction andhaving an annular surface which forms with the side wall of the opening a shaft seal, a gear mounted on said spindle and keyed thereto, a horizontally extending drive shaft mounted on said frame construction within the enclosed space, a gear chain providing a positive driving connection between said gear and said drive shaft, and a gear chain connecting said drive shaft to each of said rollers whereby said rollers are driven synchronously.

7. In a window construction, the combination of, a pair of window panes positioned in spaced parallel relationship, a rigid frame construction providing mounting means for said panes and forming with said panes a sealed enclosure, a pair of shade rollers rotatably mounted within said sealed enclosure in parallel relationship respectively at the top and bottom edges of said panes, a pair of shades wound respectively on said shade rollers, a pair of connecting strips at the respective side edges of said panes connecting the free ends of the two shades together whereby the winding of the strips onto one roller unwinds the shade from the other roller and draws the shade between the panes to cover the window, a gear box attached to the bottom of said frame construction and enclosing a portion of said enclosed space, said gear box having a wall which has an opening therethrough defined by a frusto-conical surface, and a gear assembly mounted in'said gear box and adapted to transmit rotational movement through said opening into the sealed enclosure to rotate the shade rollers, said gear assembly including, a spindle rotatably mounted in said gear box and extending through said opening, the spindle having a tapered portion the surface of which mates with said frusto-conical surface to provide a shaft seal, and means forming a releasable clutch connection for transmitting rotation to said spindle and thence into the sealed enclosure which means includes a spring exerting a force urging the mating surface of said spindle against said frusto-conical surface.

8. In a window frame construction, the combination of, a pair of window panes positioned in spaced parallel relationship, a rigid frame construction providing support for said panes and including means sealing the edges of said panes to provide a sealed enclosure, a gear box mounted on said frame construction and open to said enclosure and including a wall portion having an opening therethrough into said enclosure, a spindle mounted in said opening and having a sealing surface which cooperates with the periphery of said opening to provide a shaft seal around the spindle, a releasable clutch assembly connected to the end of said spindle outside of said sealed enclosure, an operating shaft releasably connected to said clutch assembly, an operating knob fixed to said operating shaft, and a shade roller mechanism mounted within said sealed enclosure and connected to and operable by rotation of said spindle whereby a shade may be drawn between the panes.

9. In a window construction of the character described, a wall forming a part of a sealed enclosure and having an opening therethrough, a drivable mechanism in said enclosure, and a mechanism driving piece positioned in said opening to transmit movement to said mechanism, said driving piece acting as a plug in said opening and said driving piece and the wall forming said opening having cooperating surfaces which matev and prevent undesired leakage of air a cund ;a dr vin pie e a d through said a shade roller rotatably mounted within the ,sealed window enclosure at the top thereof, a" shade roller rotatably mounted within the sealed window enclosure at the bottom thereof,

a shade adapted to cover the entire window rolled upon the upper roller, a shade adapted to cover v the entire window rolled upon the lower rollerffneans at the two vertical edges of the window'connectm together "the free ends of 'the shades, shade-operating mechanism within the enclosure for driving said rollers in either direction to unroll either shade and thus selectively cover the window from the top down and from the bottom up, said window construction including a wall having an opening therein, and an actuating piece passing through said opening and operatively engaging said shade operating mechanism, said actuating piece acting as a plug in said opening cooperating with the opening to inhibit leakage of air into the enclosure.

11. In a window construction of the type wherein a pair of window panes are supported by a rigid sealed frame construction to provide a sealed enclosure and wherein shade means is provided within the sealed enclosure, the combination of wall means fixed to the frame construction and having therein an opening to the sealed enclosure which opening presents a peripheral valve seat which tapers and flares outwardly with respect to the sealed enclosure, a spindle rotatably mounted in said opening and having a mating surface which fits said valve seat thereby to provide a shaft seal, said spindle having at its end outside of said opening a threaded axial bore and having an annular row of clutch teeth surrounding said axial bore, a

clutch plate resting against the last named end of said spindle and having an annular row of teeth interengaging the teeth on the spindle, the clutch plate having a central bore in alignment with the axial bore in the spindle, a coil spring urging said clutch plate against said spindle with the teeth interengaging and also urging the spindle against said valve seat, and a driving shaft removably coupled to said clutch plate and removable to permit the insertion of a valve-lifting rod which is threaded into the axial bore in said spindle to draw said spindle away from said valve seat and thereby openthe valve.

12. In a window construction of the type having a pair of panes held in rigid spaced relationship by a frame construction which forms with the panes a sealed enclosure, a shade operating mechanism mounted within said sealed enclosure, a shade mounted on said shade operating mechanism to be moved between saidpanes, a spindle rotatably mounted in a wall of said frame construction to transmit rotary movement to said shade operating mechanism to operate said shade, said spindle forming with the wall a shaft seal, a clutch plate engaging said spindle outside of said sealed enclosure and forming therewith a releasable clutch, a spring urging said clutch plate and spindle into interengagement, and means to limit the movement of said shade operating mechanism.

13. In a window construction of the type havssei'nblies mounted within the sealed enclosure "oppositee'dges of thepanes, each roller assema; roller shaft and a roller roted-fon the shaft and means providing-a non' rigid driving connection between the roller and the shaft, shademeans adapted; to be woundon one-ofsaid' 'rollersg strip means connected'to the shade meansand adapted to'be wound on the other of said rollers, and'm'ea'ns ""ecting-said roller-shafts to be driven from outside of the enclosure.

14. In a window construction of the type having apa'ir 50f panes held in rigid spaced relationship by a frame construction which forms with the panes a sealed enclosure, a pair of roller assemblies mounted within the sealed enclosure at opposite edges of the panes, each roller assembly comprising a roller shaft and a roller rotatably mounted on the shaft and means providing a non-rigid driving connection between the roller and the shaft, shade means adapted to be wound on one of said rollers, strip means connected to the shade means and adapted to be wound on the other of said rollers, and gear means forming a gear chain and connected to said roller assemblies to rotate said rollers to wind and unwind said shade, said gear means including a rotatable drive shaft having a threaded portion, a stop nut threaded and movable upon said threaded portion and upon rotation of the drive shaft movable a limited distance therealong whereby the extent of rotation of the rollers is limited.

15. In a window construction of the type having a pair of panes held in rigid spaced relationship by a frame construction which forms with the panes a sealed enclosure, a pair of roller assemblies mounted within the sealed enclosure at opposite edges of the panes, each roller assembly comprising a roller shaft and a roller rotatably mounted on the shaft and means providing a non-rigid driving connection between'the roller and the shaft, shade means adapted to be wound on one of said rollers, strip means connected to the shade means and adapted to be wound on the other of said rollers, gear means forming a gear chain and connected to said roller assemblies to rotate said rollers to wind and unwind said shade, said gear means including a rotatable drive shaft having a threaded portion, a stop nut threaded and movable upon said threaded portion and upon rotation of the drive shaft movable a limited distance therealong, means to operate said gear means, and a clutch having separable elements connected respectively to the gear operating means and said gear means to transmit driving movement to said gear means said separable elements separating when said stop nut reaches either end of said threaded portion to release said clutch and thereby prevent further rotation of said rollers,

16. In a window construction of the type having a pair of panes held in rigid spaced relationship by a frame construction which forms with the panes a sealed enclosure, a pair of roller assemblies mounted within the sealed enclosure at opposite edges of the panes, each roller assembly comprising a roller shaft and a roller rotatably mounted on the shaft and means providing a nonrigid driving connection between the roller and the shaft, shade means adapted to be wound on one of said rollers, strip means connected to the shade means and adapted to be wound on the 11 other of said rollers, a gear assembly gearing said roller shafts together comprising two roller gears mounted on the gear shafts and a connecting shaft extending between the roller shafts and carrying two gears which mesh respectively with said roller gears, and mounting means for the end of each of the roller shafts opposite the roller gear comprising a sleeve bearing carried by the j roller shaft and a stud bolt threaded into the REFERENCES CITED The following references are of record in the file of this patent:

Number 15 Number 12 UNITED STATES PATENTS Name Date Castner July 31, 1888 Morgan May 7, 1901 Sapp 1 Oct. 6, 1903 Fox Aug. 3, 1937 Simon Aug. 29, 1939 Stucki July 15, 1941 Cavanaugh Apr. 28, 1942 Charpenning Feb. 1, 1944 Simon Mar. 7, 1944 FOREIGN PATENTS Country Date Austria 1939 

